Sunday, June 03, 2012

The silly season

They keep coming and sometimes it seems as if they come in bundles of ten. What are 'they'? Half cocked theories published in journals which really should do some checking before giving them credence and from people whose pedigrees suggest they should know better. Wild assumptions do not a theory prove. Especially when sooooo many other so called facts in the published papers are just downright wrong.

But then a judicial review is on the horizon, and true to form the beneficiaries of the badger v. cattle polemic are rising to the occasion. This time, trying (once again) to prove this huge undiscovered reservoir of bTB in cattle, researchers from Liverpool made some pretty wild leaps of faith and connected incidence of liver fluke with an alleged failure of the skin test. The 'science' journal Nature published this, obviously without checking the detail. Jumping off the page was the assertion that preMT began in 2001. It did not, that was 2006 - but let that pass.

Lumping New Zealand with the UK and Ireland, as a country with a wildlife reservoir and bTB problems in cattle is also overstating the facts. After a twenty year blitz on its TB infected possums, by 2013 NZ hopes to achieve TB free trading status, while ignoring our wildlfe reservoirs has ensured that the heap of sentinel slaughtered cattle in the UK and Ireland, continues to grow. For the record, NZ has achieved 0.35 per cent incidence in its cattle herds in 2010/11; but herd restrictions were applied in around 24 per cent of cattle herds in the west of England and Wales, with a GB average of 10 per cent. Hardly comparable.

But the assumption of specificity of the intradermal skin test with a mean average of 80 percent is the core of the paper. Thus it is missing shed loads of cattle - all with liver fluke? But the specificity of the skin test need not be 'assumed' at all. From a F O I request, Defra answered this question recently thus:

"... the SICCT test specificity in GB would be at least 995.9 per 1000 or 99.59%. Given that the majority of skin test reactors detected in GB originated from endemic TB areas of England and Wales and were likely to be infected (regardless of post-mortem findings), a better estimator of the true test specificity would be the converse of the proportion of test reactors observed in a very low TB incidence area such as Scotland, where the majority (but not all) of the test reactors could be expected to constitute false positive test results. Since we had a rate of 0.8 tuberculin skin test reactors per 1,000 animal tests in Scotland in the first nine months of 2010, this means that the test specificity was about 999.2 per 1,000 (or 99.92%). Therefore, in addition to the field trials carried out by Lesslie et al. in the mid-1970s, the current field data continues to indicate a very high specificity of the SICCT test ... "

And for once, Defra's answer to this paper's publication was spot on. If the skin test was missing millions of cattle - up to 20 % the paper asserts - then not only would this happen in all other countries using the test (unless Faciola hepatica is unique to the UK as well) but eventually all these infectious cattle would end up with gross lesions in the abattoir. A Defra spokesperson told Farmers Guardian that:

"..... research showed that ‘cattle that have both liver fluke and bTB still test positive for bovine TB, and would be culled to control the disease. The absence of positive cases of bovine TB in some areas coinciding with large amounts of liver fluke cannot be used to claim liver fluke is hiding cases, as cattle carcases are inspected in abattoirs and we would see evidence of TB in the slaughtered animals if this was the case."

Assuming this paper is correct in its many 'assumptions' that would mean about 20 per cent of all cattle slaughtered in the UK were riddled with liver fluke and also bTB would it not?
The UK cattle herd is around 9.6 million animals. Annual slaughterings involve about 3.5 million cattle so 700,000 or thereabouts should have lesions? Yes? No?
Just 1013 were confirmed with bTB at abattoir inspections in 2011.
That is the huge 'reservoir' which attracts so much hot air.

And this week, Nature ran another paper, this time from Donnelly and Woodroffe, claiming that no one could really count badgers and thus the 70 percent clearance in the proposed pilot culls may be breached, leading to compliance problems with the Bern Convention. As one comment on this story pointed out, Bern has yet to have grasped the ecological impact of too many badgers - particularly on hedgehogs.

Northen Ireland too has the begging bowl out. In this oral presentation, the Oliver syndrome is much in evidence. Please may we have some more porridge research cash? On top of the £3.5 million already spent of course.

And again some repeated wild assumptions about the skin test sensitivity (see above) and mathematical models based on mathematical models based on ... And Rosie Woodroffe's assertion seems to have gathered credence with the telling. Did you know that dead cattle spread TB?

Felling a single tree needs an 'ecological impact' assessment, so how much more 'impact' was there when these modellers cleared 11 million animals from the landscape in 2001? Thousands of acres were barren with altered cropping, long grass, funeral pyres and noise. And vitally for badgers, no grazing cattle or sheep. There was nothing for badgers to eat and so they moved. Woodroffe opined that delayed cattle tests 'were the only explanantion' for the spike in badger TB and thus cattle had given the disease to badgers. Rubbish. The whole ecology changed for that year, and the badgers moved out to find the nearest live cattle. They met resident badgers and fought. Result? Perturbation and TB, which they brought back with them when they returned back to restocked farms in the heartlands of this bloody carnage.

As well it being the silly season, on 25th June there's a Judicial Review coming up, and jobs to protect. These people need another cause.